1. Field of the Invention
The invention relates to clutch units of the oil shear type, and particularly to units having interleaved clutch plates and discs which are alternately clamped together or separated in an axial direction. The invention is directed toward a very large size clutch unit such as would be found in an aircraft catapult system for selectively winding or tensioning a nylon belt or tape which is in turn connected to a carriage secured to the aircraft to be launched or catapulted.
2. Description of the Prior Art
My U.S. Pat. No. 3,696,898 issued Oct. 10, 1972 shows a clutch-brake unit in which a plurality of interleaved clutch discs and plates are provided, all of which are simultaneously actuated by a single piston. The arrangements shown in this patent would be unsatisfactory for the purpose of actuating large size clutch units which must transmit high horsepowers. Among the problems to be dealt with in the construction of large size oil shear type clutch units are the need for maximum application of forces to couple the plates and discs, the cooling requirements for the parts, and most importantly, the need for minimizing residual drag. To illustrate the magnitude of residual drag problems, it should be noted that in an 85,000 horsepower clutch operating at 1200 R.P.M., the residual drag is in the order of 8-10,000 horsepower. The residual drag in the apparatus of the present invention, on the other hand, is less than 500 horsepower.